A zinc tetranuclear cluster Zn4O (OCOR)6 containing zinc atoms as a nuclear metal is known to be produced by subjecting a zinc carboxylate salt such as zinc (II) acetate hydrate to high-temperature (250° C. or above) heating conditions under vacuum (Non Patent Document 1).
Moreover, when zinc trifluoroacetate hydrate is used, a zinc tetranuclear cluster Zn4O (OCOCF3)6 can be obtained under the above-described reaction conditions. Furthermore, the zinc tetranuclear cluster Zn4O (OCOCF3)6 is known to be useful as a catalyst for esterification reaction, transesterification reaction, acylation reaction, and amidation reaction (Patent Document 1).
In other words, the use of the zinc tetranuclear cluster Zn4O (OCOR)6 as a catalyst allows the reactions to proceed efficiently under mild conditions. In addition, the zinc tetranuclear cluster catalyst having zinc atoms with a relatively low toxicity as a nuclear metal is known to be useful because of its environmentally benign characteristics (Non Patent Document 2).
Citation List
Patent Literature
    Patent Literature 1: WO2007/066617    Non Patent Literatures    Non Patent Literature 1: Jikken Kagaku Kouza (Experimental Chemistry Course), fourth edition, (1991), vol. 17, (Muki Sakutai·Kireto Sakutai (Inorganic Complexes and Chelate Complexes)), p. 451 to 452, (published by Maruzen Publishing Co., Ltd.)    Non Patent Literature 2: Chem. Commun. 2006, p. 2711.